Packard Forum Index » Post-War (1946-54)

Several older responses also referred to timing, so I'm going to give it a try, but am not sure what I will be listening for.

As you advance the timing, you'll be listening for the onset of heavy preignition (spark knock).

I am also curious what effect a lead substitute gasoline additive has (good or bad) on the operating temperature of the engine.

None.

I'd be a lot more comfortable knowing what the temperature danger zone is for this engine,

Someone else may well have a better answer but I'd say the point at which the coolant boils is at or even beyond the point at which you should shut it down. Problem is, the steam will exit from the radiator overflow tube which is at the base of the radiator so if you're driving along you'll not likely be able to see it, though you should be able to see it when the car is at a standstill. Whatever you do chose to do, DO NOT add cold water to the radiator of an overheated engine or you risk cracking the block. Rather, either let it cool or add it very slowly with the engine running to minimize the risk.

Without going back and looking again at the prior posts, has the radiator and block been treated and back-flushed with a chemical cooling system cleaner like oxalic acid? Have you had the radiator tested for flow-rate? Perhaps it's time to consider a radiator test and possible recore. Water distribution tube been checked? Undersize tail pipe or muffler? Incorrect fan belt fit in the water pump pulley? What's the distance between the fan blades and the radiator core?

I have to agree with Owen and others on prior posts about the bashing and tone of posts here. I dont know Fred but J from kanter( i assume both are from the vendor) was and has been helpful in other threads and I would think driving them or anyone away would be a disservice to us all. As far as the timing, sbc do indeed have the timing groove on the outer ring and I have seen them migrate on the rubber. To set timing you may advance slightly (2-3) deg at a time. If the idle picks up drive the car. If no pinging exists under load repeat. This may be done until pinging is reached or until engine temp is acceptable. If ping is encountered in heat under load back off 2 or 3 deg.

I posted this tid-bit on another overheating problem. My 51 200 Packard 288 engine was overheating but not boiling over. The temp was almost all the way to the right...HOT....The temp gau.. DID drop when ever I was on a slight downgrade or no up hill of any sort. I did all the posted checks and possible fixes but nothing worked until I used a vacuum pump and checked the vacuum advance.....EUREKA......the advance did NOT work.......happy days, found something significant. Pulled the dist, sent the advance to Jason at AE(R)?, and had it fixed. I don't have any heating problem now, even when the ambient temp is 95 to 99 degrees(this summer Vancouver, WA). The temp ga., stays right in the middle. Hope this helps.

Regards,
Steve

IMHO, After seeing the number of posts, I believe something has not been tested/verified/replaced, etc., and the answer already lies somewhere between the SECOND and LAST post.

Thanks for the response.

Is there a simple explanation why the engine runs hotter when the timing is off?

Just so I am clear, changing the timing from 4 deg BTDC to 6 deg BTDC would be advancing the timing? And Sam found that 12 deg BTDC worked best for his car?

...has the radiator and block been treated and back-flushed with a chemical cooling system cleaner like oxalic acid?

No

Have you had the radiator tested for flow-rate? Perhaps it's time to consider a radiator test and possible recore.

Radiator was recently recored.

Water distribution tube been checked?

Scoped it when I recently replaced water pump. Looked very clean and in very good shape.

Undersize tail pipe or muffler?

Recently replaced entire exhaust system with stock system.

Incorrect fan belt fit in the water pump pulley?

Recently replaced with Gates 26501 (is that an appropriate replacement part?). Seems to fit well (flush with top edge of pulley and is not riding on bottom of pulley).

What's the distance between the fan blades and the radiator core?

1.25"

Thanks again.

Hi Don,

I don't know if lead additive in the gas would help or not, but for what it's worth I use ethanol free hi-test.

I know how frustrating this problem can be. Sounds like you've gone through the major areas, so keep playing with the timing like OD and customclipper55 suggested, and check the vacuum (as packardguy53 found).

Hang in there - you will find it!

Wow!, This thread really has it's ups and downs.

Anyway, it looks like the most benefit for the overheating problem came from using a thermostat. I used to drill two 1/8 bleed holes to ensure no motor damage should the darn thing fail.

In almost all motors the rear cylinders are running hotter than the front. Motors with the pumps and return necks midway do a lot better. If the pump is midway and the return is in the front there is still a bottle neck. Sediments as well accumulate at the back of the motor owing to the directional change of the flow.

On the issue of timing, the reason late timing makes an engine run hotter is because combustion is faster under higher compression. Thus, retarded timing results in a slower burn which is less thermally efficient than a faster explosion. For an overheating problem that can't be solved with the usual suspects I would look at the distributor. If the dwell is changing with RPM this may be causing maverick sparks or late timing at low compression. On Junior Packards the timing marks are pretty lousy and have to be carefully searched out and marked.

Another problem is that old metal has absorbed a lot of oxygen which inhibits thermal transfer. Well cared for motors do a lot better, but rusty and eroded water jackets may run hotter without a solution. Ken Fahnestock had a Marmon 16 that ran hot because the block sat empty for years and the aluminum was corroded.

Tim, I agree with your words about coolant flow and debris build up. I must have taken pound of rust and build up out of the left rear bank on my 1939 Cadillac V-8. The water pump located on the front of the right hand bank, was about as far away as it could be.

Also, agree with your comments on ignition timing affecting cooling. I had the vacuum advance chambers fail on two of my Packards. They started running hot and a quick check revealed the vacuum advances were no longer working. This malfunction was effectively retarding the timing. After new chambers were installed the operating temp returned to normal.

(o{}o)

I agree JW, and add that ANY vacuum leak can give very lean mixtures and contribute to hot running. I recently saw a Twelve with a piston head burned thru from long-time running with a large vacuum leak. I wonder how many newcomers to older cars realize the value of using a vacuum gauge to analyze engine performance.

Thanks one and all for the info. The vacuum advance was working properly. When I advanced the timing as far as possible mechanically, it sounded about the same as when timed per specs, if not a little stronger. I also installed a separate Bourdon Tube type temperature gauge and was pleased to find the running temperature was a steady 190? in the summer (a little less in cold weather with a new 180? thermostat). Once the weather warms up I plan to readjust the timing back to 6? BTDC and see if the running temp changes. I may eventually reconnect the original temp sender to see where the 190? mark is on the in-dash gauge. I'd also like to see if the TDC timing mark is still on the money. Any advice on the most accurate way to do this?

I went through the same thing with my 288.I found out at last that the valves were too tight.Opened them up to .009 and.013.Its a little bit noisier but it now runs middle of the temp gage.